Photoresists are applied to substrates for semiconductors, e.g., silicon wafers, glass substrates for flat displays or kinds of substrates for electric circuits (hereinafter called substrate) but photoresists may not be uniform on the edges of the substrates. Due to this, the photoresist is not removed and remained on the edges and may cause the dust in the proceeding process. Therefore, the photoresist needs to be removed from the edges of the substrate before the process proceeds.
A negative-type photoresist is used in an electrode forming process of a plate process, and a positive-type photoresist is used to prevent resist film at the peripheral portion from separation.
Japan unexamined patent publication No. 2005-505147 discloses an apparatus having a ring-shaped light blocking body placing on a substrate to cover whole edges of the substrate. Since the light blocking body discloses in the publication No. 2005-505147 has a shape to cover whole edges of the substrate, when the substrate is loaded or unloaded, the substrate table is required to be moved to move the light blocking means in the waiting position so that the light blocking means is removed. Thereafter, the substrate table is moved to the substrate loading position and the substrate is changed, and the substrate table is moved to the waiting position to place the light blocking body on the substrate. Therefore, the moving distance of the substrate table is long, so that it takes time to load and unload the substrate. Moreover, the light blocking body is moved frequently, which causes the high possibility of dust filling up.
Japan unexamined patent publication No. 2005-045160 discloses a technique of an arc-shaped light blocking unit or a rectangular light blocking unit being placed near the edges of the wafer not to expose the peripheral region of the substrate. This technique requires the mechanism of moving the light blocking unit around the substrate and the mechanism of calculating and controlling the light blocking position.
Patent publication 1: Japan unexamined patent publication No. 2005-505147
Patent publication 2: Japan unexamined patent publication No. 2005-045160